Early diagnosis of cancer by detecting the chemiluminescence of hematoporphyrins in peripheral blood lymphocytes.

Early detection and optimal treatment are the most effective means to improve cancer mortality. Mass screening for cancer has yielded a marked reduction of cancer mortality in the United States. Simple and effective methods are expected for screening of malignancy. Hematoporphyrin derivatives (HPDs) are known to accumulate in cancer cells; thus, HPD has been used for local diagnosis and photodynamic therapy of cancer. The lymphocytes of cancer patients also demonstrate the active uptake of HPD and this phenomenon has been applied for the diagnosis of cancer. In the present study, we have developed a novel method for measurement of the chemiluminescence of HPD in peripheral blood lymphocytes. HPD is composed of hematoporphyrin and its oligomers. Seven cancer patients and seven controls were recruited for this study. The primary cancers included two prostate cancers (one without metastasis and the other with lung metastasis), a renal cancer, a lung adenocarcinoma with systemic metastasis, two gallbladder cancers with lung metastasis, and a colon cancer with liver metastasis. HPD in lymphocytes was measured using a highly sensitive chemiluminescence analyzer with laser light irradiation to detect photoemission by (1)O(2) from HPD. The intensity of chemiluminescence exhibited a linear correlation with the concentrations of HPD. In addition, the level of HPD in lymphocytes was significantly higher in cancer patients than that in healthy volunteers (p < 0.05). These results suggest that detection of the chemiluminescence of HPD in lymphocytes could be a sensitive and simple method for cancer diagnosis and screening.

The combined treatment of transplantable solid mammary carcinoma in Wistar rats by use of photodynamic therapy and cysteine proteinase inhibitor.

Numerous studies have shown that lysosomal proteinases play an important role in carcinogenesis. The enzymatic activity of tumor-associated proteases is counter-balanced by specific inhibitors. Photodynamic therapy (PDT) is a technique which involves photoexcitation of sensitizing drugs retained in neoplastic tissue that is subsequently destroyed. Intraperitoneal injections of hematoporphyrin derivative (HpD) were given at a dose of 20 mg/kg in rats transplanted with mammary carcinoma. A halogen lamp was used 24 hours later at 630 +/- 20 nm and total dose--200 J/sq.cm. Cysteine proteinase inhibitor (CPI) was dissolved in saline and injected subcutaneously in doses of 50 mg and 200 mg per animal. The effectiveness of the treatment was evaluated with regard to survival time and tumor response and to depth of necrosis. In several cases tumors completely disappeared following HpD-PDT + CPI. The number of complete tumor responses was higher when PDT + 200 mg of CPI was used, i.e. 6 out of 10 rats. Promising results have also been obtained with regard to survival time of treated animals and to induction of tumor necrosis. We may presume that a combination of PDT and proteinase inhibitors could be a useful tool in further anticancer studies and, hopefully, in anticancer therapy.

Biological effects of photoactivated-HPD and cholesteryl hemisuccinate on erythroid differentiation.

In order to establish the ability of porphyrins to distinguish between differentiated and undifferentiated cells of the erythropoietic pathway, the cytotoxic effects of hematoporphyrin derivative (HPD) on Friend erythroleukemic cells (FLC) were derivative (HPD) on Friend erythroleukemic cells (FLC) were studied. Since cholesterol affects the fluidity of cell membranes, the inhibitory effect of cholesteryl hemisuccinate (CHS) on HPD was similarly tested. FLC were induced with either dimethyl sulfoxide (DMSO), hemin, or both. The cells responded to DMSO-treatment by the synthesis of a large amount of hemoglobin and a decrease in both the cell volume and rate of cell-growth. Hemin, on the other hand, did not drive FLC to synthesize hemoglobin and reduced only moderately the growth rate compared to untreated cultures. The combined effect of DMSO and hemin led to a profound inhibition of the growth rate, but did not increase the synthesis of hemoglobin compared to the level observed in cells treated with DMSO only. The binding property of HPD to FLC was also determined. DMSO-treatment significantly reduced the amount of HPD-binding, and combined treatment with DMSO and hemin resulted in even a lower level of HPD-binding. On the other hand, induced as well as non-induced cells showed the same sensitivity to photoactivated HPD when both DNA and protein synthesis were examined. Pretreatment of both differentiated and undifferentiated cells with CHS reduced the cytotoxicity of photoactivated HPD to the same level. We conclude that the decreased binding of HPD to differentiated cells is a result of a reduction in their cell volume. Thus, the differentiation process per se does not protect cells against the photodynamic effect of HPD. Moreover, CHS may act as a scavenger or first acceptor of singlet oxygen blocking the photodynamic effect.